Contraction of cold neutron star due to in the presence a quark core

Motivated by importance of the existence of quark matter on structure of neutron star. For this purpose, we use a suitable equation of state (EoS) which include three different parts: i) a layer of hadronic matter, ii) a mixed phase of quarks and hadrons, and, iii) a strange quark matter in the core. For this system, in order to do more investigation of the EoS, we evaluate energy, Le Chatelier's principle and stability conditions. Our results show that the EoS satisfies these conditions. Considering this EoS, we study the effect of quark matter on the structure of neutron stars such as maximum mass and the corresponding radius, average density, compactness, Kretschmann scalar, Schwarzschild radius, gravitational redshift and dynamical stability. Also, considering the mentioned EoS in this paper, we find that the maximum mass of hybrid stars is a little smaller than that of the corresponding pure neutron star. Indeed the maximum mass of hybrid stars can be quite close to the pure neutron stars. Our calculations about the dynamical stability show that these stars are stable against the radial adiabatic infinitesimal perturbations. In addition, our analyze indicates that neutron stars are under a contraction due to the existence of quark core.Comment: 10 pages, 3 figures, 4 table

Structure of Neutron Star with a Quark Core

The equation of state of de-confined quark matter within the MIT bag model is calculated. This equation of state is used to compute the structure of a neutron star with quark core. It is found that the limiting mass of the neutron star is affected considerably by this modification of the equation of state. Calculations are carried out for different choices of the bag constant.Comment: 19 pages, 8 figure

Experimental Data Assessment Test for Diamondoids Solubility in Gaseous System

The financial support of the ANR (Agence Nationale de la Recherche) and OSEM (Orientation Stratégique des Ecoles des Mines) is gratefully acknowledged. Ali Eslamimanesh wishes to thank MINES ParisTech for providing a PhD scholarship.International audienceDeposition of solid diamond-like hydrocarbons may cause drastic problems in natural gas systems, and therefore it is of interest to know deposit conditions as accurately as possible. Unfortunately, only a few sets of experimental data for solubility of diamondoids in gaseous systems have been reported in the literature partly because of the difficulties in measurements of very low concentrations of the latter compounds in the gas phase. Thus, the reliability of the corresponding data must be checked prior to their applications. In this communication, we present the results of a thermodynamic assessment test (consistency test) based on an area test approach for experimental solubility data of adamantane and diamantane in supercritical carbon dioxide and ethane. The modified Esmaeilzadeh␣Roshanfekr (m-ER) cubic equation of state (CEoS) along with the vdW2 mixing rules are used to model the solubility of the aforementioned diamondoids in the latter supercritical gases. The results show that all of the investigated experimental data sets seem to be thermodynamically consistent

Glycol Loss in a Gaseous System: Thermodynamic Assessment Test of Experimental Solubility Data

International audienceTriethylene glycol (TEG) is generally used to adjust the water dew point in natural gas processes. Unfortunately, only very few sets of experimental data regarding solubilities of these humidity absorbents in supercritical natural gas components have been reported in the literature partly due to the difficulties in such very low concentration measurements. Therefore, a satisfactory accuracy of measurements is not obvious, and the reliability of the corresponding data must be checked prior to their application. In this study, we focus on presenting the results of a thermodynamic assessment test (consistency test) for experimental solubility data of triethylene glycol in supercritical methane and carbon dioxide. The Gibbs Duhem equation in terms of pressure, fugacity coefficients, solubilities of triethylene glycol in gas phase, and compressibility factor of gas phase is applied for the consistency test. The Soave-Redlich-Kwong (SRK) equation of state (EoS) along with the van der Waals (vdW2) mixing rules is used to represent the corresponding solubilities. The results show that three sets of the four investigated experimental data sets are thermodynamically consistent, while one data set is not fully consistent